In general, an incandescent lamp or a fluorescent lamp has been mainly used for indoor or outdoor lighting. Such an incandescent lamp or a fluorescent lamp has a problem that its life is short and there is a need of frequent replacement. To solve this problem, there has been developed a lighting fixture that employs an LED excellent in controllability, quick response speed, high photoelectric transformation efficiency, long life, low power consumption, and high brightness.
In other words, a light emitting diode (LED) has advantages of consuming less power with the high photoelectric transformation efficiency, requiring no preheating time because the light emission is not based on heat and electric discharge, and being quickly turned on and off.
Further, advantageously, the LED is strong on a shock and safe because there are no needs of gas or filaments, consumes less power because stable direct-current (DC) lighting method is employed, operates at high repetitions and pulses, reduces fatigue of optic nerves, is usable semi-permanently, has lighting effects with various colors, and is miniaturized using small light sources.
However, the LED generates more heat as its power increases, and it is thus important to dissipate heat. In the case where the power of the LED is lowered to generate less heat, more LEDs are needed to reach desired power, thereby causing a problem of increasing the volume and weight of the LED lighting fixture. In particular, when the volume and weight of the LED lighting fixture are increased, there are difficulties in installation and maintenance.
Further, when the LED is applied to a visible ray searchlight or an infrared surveillance camera, efficiency in straight propagation of light is important. In this case, when the power of the LED is lowered, the straight propagation of light is deteriorated and a visible range is decreased.
As the prior art literatures, Korean Patent No. 10-1333009 (tilted ‘LED LIGHTING APPARATUS FOR ANTI-GLARE,’ published on Nov. 27, 2013).